Vibration-assisted thermal bonding (VATB) of CF/PEEK thermoplastic composites: Influence of bonding parameters on the lap shear strength

Thermoplastic composites excel in fatigue and impact resistance compared to thermoset composites. Notably, they allow in-situ consolidation using Automated Fiber Placement (AFP), which reduces manufacturing costs and energy consumption. However, AFP’s short processing time poses challenges in achieving optimal bond strength. To address this, the current research introduces an innovative technique called vibration-assisted thermal bonding (VATB). This method combines material preheating with sub-ultrasonic vibration during bonding to enable rapid, high-quality consolidation. The simultaneous application of heat and vibration raises the material temperature to its melting point and reduces polymer viscosity, respectively. To evaluate the effect of frequency-dependent vibratory pressure on consolidation quality, a custom machine integrating electrical heating and vibratory pressure was developed. The study systematically investigates the influence of bonding parameters such as preheating time, mold temperature, holding time, consolidation pressure, and vibration frequency. Lap shear strength is used as the key metric for evaluation. Results show VATB significantly improves bonding strength compared to conventional thermal bonding, with increases of up to 85 % at 355 ∘ C and 22 % at 375 ∘ C. These improvements are attributed to enhanced polymer chain penetration and shear-thinning effects, enabling stronger bonds at lower temperatures and shorter times, reducing post-treatment needs and costs. • Introduced a fast bonding method for thermoplastic composite materials. • Designed and manufactured a novel setup to combine heat and vibration precisely. • Leveraged shear-thinning property to improve polymer flow and enhance bonding strength. • Used vibration and heat to improve bonding quality at lower temperatures. • Reduced bonding time while increasing strength up to 85 % over standard methods.